import { ITPAParams } from './generateTPAParams';
export declare const cssFunctions: {
    join: (color1: any, strength1: any, color2: any, strength2: any) => string;
    color: (colorValue: any, tpaParams: ITPAParams) => any;
    font: (font: any, tpaParams: ITPAParams) => string;
    opacity: (color: any, opacity: number) => string;
    withoutOpacity: (color: any) => string;
    string: (value: string) => string;
    darken: (colorVal: any, darkenValue: number) => string;
    lighten: (colorVal: any, lightenVal: number) => string;
    whiten: (colorVal: any, whitenVal: number) => string;
    number: (value: number | string) => number;
    underline: (font: any) => string;
    unit: (value: number | string, unit: string) => string;
    fallback: (...args: any[]) => any;
    direction: (value: string, tpaParams: ITPAParams) => string;
    zeroAsTrue: (zero: any) => any;
    calculate: (operator: any, ...args: any[]) => any;
    readableFallback: (baseColor: string, suggestedColor: string, fallbackColor: string) => string;
    /**
     * Given foreground and background colors, checks to see if the colors are readable together.
     * If not, it returns the first to be readable among:
     * background color lightened/darkened by 1%
     * background color lightened/darkened by 5%
     * background color lightened/darkened by 10%
     * background color lightened/darkened by 20%
     * background color lightened/darkened by 30%
     * background color lightened/darkened by 40%
     * background color lightened/darkened by 50%
     * background color lightened/darkened by 60%
     * the method (lighten or darken) is determined by the ratio between the two given colors
     * @param foreground - the foreground (text) color
     * @param background - a background color
     */
    smartBGContrast: (foreground: string, background: string) => string;
};